Lawsuits in California and Rhode Island are taking aim at Facebook and its largest application maker, Zynga, alleging that they violated federal law by sending identifying information about their users to advertisers and Internet tracking companies.

Reuters

The complaints both cite a Wall Street Journal investigation that found the top app makers were sending Facebook user ID numbers to outside firms. These numbers could be used to look up people’s names — and in some cases other information — on the social-networking services, and they could potentially be tied to advertising preferences or other data.

California resident Nancy Walther Graf filed the suit against the app maker, Zynga Game Network Inc., alleging that the company transmitted the personally identifiable information to third parties “for substantial profit.” The suit was filed in U.S. District Court in the Northern District of California Monday afternoon. In it, Ms. Graf says Zynga’s use of the data without users’ permission violated federal laws that protect the privacy of electronic communications, as well as a California computer-crime law.

“We believe that the complaint is without merit and we intend to defend against it vigorously,” said a spokeswoman for a Zynga, which makes the popular FarmVille and Texas HoldEm Poker apps, in an emailed statement.

A lawyer for Ms. Graf said the suit targets Zynga rather than Facebook because Facebook’s policies prohibit app makers from transferring data about users to outside advertising and data companies.

“These third parties like Zynga, if they’re going to get access to personally identifiable information in order to make these applications more useful to Facebook users, they’re going to have to be trusted with that information,” said attorney Kassra Nassiri in an interview.

The Rhode Island suit, however, alleges that Facebook bears responsibility for the breach. The suit was originally filed by in June in U.S. District Court in Rhode Island over an earlier breach and was amended Monday to include the latest incident. It relies on one of the same federal laws cited in the Zynga case.

A Facebook spokesman said in an emailed statement that the company believes there is no merit to the suit and plans to fight it.